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References: <20201016043513.119841-1-andrew@aj.id.au> <20201016043513.119841-3-andrew@aj.id.au>
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From:   Joel Stanley <joel@jms.id.au>
Date:   Wed, 21 Oct 2020 05:05:11 +0000
Message-ID: <CACPK8XeiPBPyLu5pvjCgYquCKh+PynVKGyibUSAi+W_xw0Awfg@mail.gmail.com>
Subject: Re: [PATCH 2/2] ARM: dts: tacoma: Add reserved memory for ramoops
To:     Andrew Jeffery <andrew@aj.id.au>
Cc:     Rob Herring <robh+dt@kernel.org>,
        devicetree <devicetree@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        linux-aspeed <linux-aspeed@lists.ozlabs.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Fri, 16 Oct 2020 at 04:36, Andrew Jeffery <andrew@aj.id.au> wrote:
>
> Reserve a 1.5MiB region of memory to record kmsg dumps, console and
> userspace message state into 16kiB ring-buffer slots. The sizing allows
> for up to 32 dumps to be captured and read out.
>
> Set max-reason to KMSG_DUMP_EMERG to capture bad-path reboots.
>
> Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
> ---
>  arch/arm/boot/dts/aspeed-bmc-opp-tacoma.dts | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/arch/arm/boot/dts/aspeed-bmc-opp-tacoma.dts b/arch/arm/boot/dts/aspeed-bmc-opp-tacoma.dts
> index 46f2f538baba..4f7e9b490e1a 100644
> --- a/arch/arm/boot/dts/aspeed-bmc-opp-tacoma.dts
> +++ b/arch/arm/boot/dts/aspeed-bmc-opp-tacoma.dts
> @@ -26,6 +26,15 @@ reserved-memory {
>                 #size-cells = <1>;
>                 ranges;
>
> +               ramoops@b9e80000 {
> +                       compatible = "ramoops";
> +                       reg = <0xb9e80000 0x180000>;

I take that r-b back. When booting, we see:

[    0.000000] region@ba000000 (0xb8000000--0xbc000000) overlaps with
ramoops@b9e80000 (0xb9e80000--0xba000000)

Which appears to be a true statement.

> +                       record-size = <0x4000>;
> +                       console-size = <0x4000>;
> +                       pmsg-size = <0x4000>;
> +                       max-reason = <3>; /* KMSG_DUMP_EMERG */
> +               };
> +
>                 flash_memory: region@ba000000 {
>                         no-map;
>                         reg = <0xb8000000 0x4000000>; /* 64M */
> --
> 2.25.1
>